The present invention claims the benefit of Korean Patent Application Nos. 15450/2002 and 15451/2002 both filed in Korea on Mar. 21, 2002, which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a liquid crystal dispensing apparatus, and in particular, to a liquid crystal dispensing apparatus capable of dispensing an accurate amount of liquid crystal onto a substrate and distributing the dispensed liquid crystal onto the substrate.
2. Description of the Related Art
Currently, the development of various portable electronic equipment, such as mobile phones, personal digital assistants (PDAs), and notebook computers, require flat panel display devices having light weight, small size, and adaptability to portable electronic equipment. Various different types of flat panel display devices have been developed for these portable electronic equipment including liquid crystal display (LCDs), plasma display panels (PDPs), field emission display (FEDs), and vacuum fluorescent displays (VFDs).
FIG. 1 is a cross sectional view of a liquid crystal display device according to the related art. In FIG. 1, a LCD 1 includes a lower substrate 5, an upper substrate 3, and liquid crystal material layer 7 arranged between the lower substrate 5 and the upper substrate 3. The lower substrate 5 is a driving element array substrate having a plurality of pixel regions formed on an inner surface thereof. A driving element, such as a TFT (thin film transistor), is formed within each of the pixel regions. The upper substrate 3 is a color filter substrate, and includes a color filter layer formed on an inner surface thereof for producing colored light. In addition, a pixel electrode and a common electrode are formed on the lower substrate 5 and the upper substrate 3, respectively, and an alignment layer for aligning liquid crystal molecules of the liquid crystal material layer 7 is coated on the lower substrate 5 and the upper substrate 3.
The lower substrate 5 and the upper substrate 3 are bonded each other by a sealing material 9, and the liquid crystal material of the liquid crystal material layer 7 is disposed therebetween. Accordingly, information is displayed by controlling an amount of light transmitted through the liquid crystal material layer 7 by driving the liquid crystal molecules with the driving element formed on the lower substrate 5.
A fabrication process of a liquid crystal display device can be divided into a driving element array substrate process for forming a driving element on the lower substrate 5, a color filter substrate process for forming a color filter on the upper substrate 3, and a cell formation process.
FIG. 2 is a flow chart of a liquid crystal display device fabrication method for forming the liquid crystal display device of FIG. 1 according to the related art. In step S101, a TFT array process is performed to include a plurality of gate lines and data lines (not shown) arranged on the lower substrate 5, thereby defining a plurality of pixel regions. In addition, a TFT is connected to the gate and data lines formed within each of the pixel regions to function as a driving element. Furthermore, a pixel electrode that contacts the TFT and drives the liquid crystal material layer 7 according to a signal applied through the TFT is formed by the driving element array process.
In step S104, red, green, and blue color filter layers and a common electrode are formed on the upper substrate 3 by the color filter process to generate colored light.
In step S102, a coating process includes forming an alignment layer on the lower substrate 3 to induce a surface anchoring (i.e., a pretilt angle and an alignment direction) to liquid crystal molecules of a liquid crystal material layer 7 formed between the upper and lower substrates 3 and 5. Then, the alignment layer formed on the lower substrate 3 is rubbed.
In step S105, an additional coating process includes forming an alignment layer on the upper substrate 5 to induce a surface anchoring (i.e., a pretilt angle and an alignment direction) to liquid crystal molecules of a liquid crystal material layer 7 formed between the upper and lower substrates 3 and 5. Then, the alignment layer formed on the upper substrate 5 is rubbed.
In step S103, spacers are uniformly dispersed on the lower substrate 5 to maintaining a uniform cell gap between the upper and lower substrates 3 and 5.
In step S105, a sealing material 9 is coated onto the upper substrate 3.
In step S107, the upper and lower substrates 3 and 5 are bonded together under pressure.
In step S108, the bonded upper and lower substrates 3 and 5 are cut and processed to form a plurality of individual liquid crystal display cells.
In step S109, liquid crystal material is injected into each of the individual liquid crystal display cells via a liquid crystal injection hole. Then, each of the individual liquid crystal display cells is encapsulated.
In step S110, each of the encapsulated individual liquid crystal display cells is inspected.
FIG. 3 is a cross sectional view of a liquid crystal injecting apparatus according to the related art. In FIG. 3, a container 12 containing liquid crystal material 14 is disposed within a vacuum chamber 10, and a liquid crystal panel 1 is placed above the container 12. In addition, a liquid crystal panel mover (not shown) is disposed within the vacuum chamber 10 to move the liquid crystal panel 1 into the container 12, thereby making contact between the liquid crystal material 14 and a liquid crystal injection hole 16 of the liquid crystal panel 1. In general, this method is commonly referred to as a liquid crystal dipping injection method.
Then, the pressure within the vacuum chamber 10 is increased by supplying nitrogen (N2) gas into the interior of the vacuum chamber 10. Accordingly, the liquid crystal material 14 is injected into the liquid crystal panel 1 through the liquid crystal injection hole 16 due to a pressure difference between the liquid crystal panel 1 and the vacuum chamber 10. Then, after the liquid crystal material 14 completely fills the liquid crystal panel 1, the liquid crystal injection hole 16 is sealed by a sealing material and a liquid crystal material layer is formed inside of the liquid crystal panel 1. In general, this method is commonly referred to as a liquid crystal vacuum injection method.
However, the liquid crystal vacuum injection method is problematic. First, a total processing time for completely injecting the liquid crystal material 14 into the liquid crystal panel 1 through the liquid crystal injection hole 16 requires a significant amount of time. Generally, since an interval between the driving element array substrate (i.e., lower substrate 5 in FIG. 1) and the color filter substrate (i.e., upper substrate 3 in FIG. 1) of the liquid crystal panel 1 is about a few xcexcm, a very small amount of liquid crystal material 14 per unit time is injected into the liquid crystal panel 1. For example, during fabrication of a 15 inch liquid crystal panel, total processing time for completely injecting the liquid crystal material 14 into the liquid crystal panel 1 may be 8 hours. Accordingly, fabrication efficiency of the liquid crystal panel 1 is low.
Second, a liquid crystal material consumption rate is very high. Compared to the amount of the liquid crystal material 14 placed into the container 12, the amount of liquid crystal material 14 actually injected into the liquid crystal panel 1 is very small. Moreover, when the liquid crystal material 14 is exposed to the atmosphere air or to certain gases, the liquid crystal material reacts deteriorates. Furthermore, the liquid crystal material 14 deteriorates by the flow of impurities during contact with the liquid crystal panel 1. Thus, any of the liquid crystal material 14 that remains in the container 12 after injection into each liquid crystal panel 1 must be discarded. Accordingly, productions costs are increased.
Accordingly, the present invention is directed to a liquid crystal dispensing apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a liquid crystal dispensing apparatus capable of cleanly dispensing liquid crystal material directly onto substrates of a liquid crystal display panel.
Another object of the present invention is to provide a liquid crystal dispensing apparatus capable of improving a liquid crystal material dispensing accuracy on substrates of a liquid crystal display panel.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a liquid crystal dispensing apparatus includes a liquid crystal material container filled with liquid crystal material a gas supply at an upper portion of the liquid crystal material container for pressurizing the liquid crystal material with gas, a needle seat positioned at a lower portion of the liquid crystal material container and having a discharge hole for discharging the liquid crystal material of the liquid crystal material container, a needle having first and second ends positioned within the liquid crystal material container to be movable along upward and downward directions, a first spring positioned at a first end of the needle, a solenoid coil positioned at the upper portion of the liquid crystal material container, a magnetic bar positioned adjacent to the first end of the needle within the solenoid coil for moving the needle along the upward direction by generating a magnetic force when power is applied to the solenoid coil, a second spring positioned around the magnetic bar within the magnetic coil, and a nozzle positioned at the lower portion of the liquid crystal material container for dispensing the liquid crystal material from the liquid crystal material container onto a surface of a substrate.
In another aspect, a liquid crystal dispensing apparatus includes a liquid crystal container filled with liquid crystal material, a gas supply at an upper portion of the liquid crystal material container for pressurizing the liquid crystal material with gas, a needle seat positioned at a lower portion of the liquid crystal container, a discharge hole formed in the needle seat for discharging the liquid crystal material, the discharge hole having a first magnetic force, a needle positioned within the liquid crystal material container to be movable along upward and downward directions, the needle having first and second ends such that the first end opens and closes the discharge hole according to a magnetic force formed at the second end, a solenoid coil and a magnetic bar positioned adjacent to the second end of the needle for moving the needle along the upward direction by application of a second magnetic force to the second end of the needle, and a nozzle positioned at a lower portion of the liquid crystal material container for dispensing the liquid crystal material onto a surface of a substrate.
In another aspect, a liquid crystal dispensing apparatus includes a liquid crystal material container filled with liquid crystal material and pressurized with gas supplied at an upper space of the liquid crystal material container, a needle seat positioned at a lower portion of the liquid crystal container and having a discharge hole for discharging the liquid crystal material, a needle positioned within the liquid crystal container to be movable along upward and downward directions, the needle having first and second ends such that the first end opens and closes the discharge hole according to a first magnetic force generated at the first and second ends of the needle, a solenoid coil positioned above the second end of the needle, a magnetic bar positioned above the needle for moving the needle along the upward direction by generating a second magnetic force when power is supplied to the solenoid coil, and a nozzle positioned at a lower portion of the liquid crystal container for dispensing the liquid crystal material onto a substrate having at least one panel.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.